Fast pyrolysis, also referred to as flash pyrolysis, is a process whereby biomass is decomposed in an environment without an oxidizing agent at temperatures of approximately 500° C. for short times (e.g., on the order of less than five seconds). Thermo-chemical biomass conversion by fast pyrolysis to bio-oil, bio-char, and bio-gas is a part of a path to an alternative energy source because of the upgrade in heating value and density such that it may be easily transported as part of a new distribution network. Effective methods of biomass conversion to bio-oil are of interest because bio-oil represents a deployable energy carrier with favorable source characteristics (e.g., it can be produced in situ and is carbon-neutral). In fast pyrolysis, biomass is pulverized, pyrolyzed, and the bio-products are recovered. Bio-oil can be used directly in boilers (e.g., for heating or electricity), or upgraded for use as a fuel.
There are a number of reactor types for the fast pyrolysis of biomass: entrained flow reactor, wire mesh reactor, vacuum furnace reactor, vortex reactor, rotating reactor, microwave reactor, fluidized-bed reactor, and the circulating fluidized-bed reactor. These reactors are complicated and require a large external energy source for operation. The fluidized-bed reactor (“FBR”) is representative of the current state of the art. The FBR requires a condenser to cool the bio-products to quench the secondary pyrolysis reactions. The condenser is an active cooling component that can lead to heat loss and system inefficiency. Primary pyrolysis reactions create the pyrolysis vapor which condenses to bio-oil, whereas secondary pyrolysis reactions adversely affect the bio-oil quality and should be avoided. Thus, improvement of thermal efficiency and control over the primary and secondary pyrolysis reactions are an objective of this invention.